Reaction Controlled Assemblies of Polyoxotungstates (-molybdates) and Coordination Polymers

To investigate the influence of reaction conditions on the compound structures, five polyoxometalate (POM)-supported inorganic−organic hybrid compounds, [CuI3(L1)4][PW12O40] (1), [CuI3(L1)4][PMo12O40] (2), [CuI3(L1)4][PW12O40] (3), [CuI3(L1)3][PW12O40] (4), and [CuI3(L2)3][PMo12O40] (5) [L1 = 1,4-bis(pyrazol-1-ylmethyl)benzene, L2 = 4,4′-bis(pyrazol-1-ylmethyl)biphenyl], were hydrothermally synthesized by tuning the reactant species and molar ratio and reaction temperature and were characterized by elemental analysis, IR spectroscopy, PXRD, XPS, electrochemistry, SPS, and X-ray crystallography. Compounds 1 and 2 were synthesized in the isostructural state at 150 °C, in which L1 ligands link CuI ions, generating a cationic 2D 63 (hcb) skeleton {[Cu3(L1)4]3+}n-like sheet that further connects with POM anions, forming a neutral 2D (3,4)-connected network with a Schläfli symbol of (53)2(54;82). In contrast, compound 3 was synthesized at a relatively lower reaction temperature (130 °C) than that for the synthesis of 1 and 2, which exhibits a similar 2D sheet-like cationic skeleton with 1 and 2. Interestingly, the POM anions do not coordinate with the cationic moieties in 3. Compounds 4 and 5 were synthesized with a relatively lower reactant molar ratio in comparison with that for the synthesis of 1−3, in which the cationic coordination moieties all present 1D chain-like structures. Compound 4 exhibits a 3D (3,4)-connected sqc74 framework with a Schläfli symbol of (6;82)(64;8;10) formed by the POM anions linking {[Cu3(L1)3]3+}n cationic chains. In comparison to 4, compound 5 shows a 3D supramolecular framework, which is formed by POM anions and {[Cu3(L2)3]3+}n cationic chains via hydrogen bonds. The structural difference of compounds 1−5 indicates that the reaction conditions perform a crucial influence on the structures of this series. The electrochemical properties of 2 and 5 and the SPS responses of 3−5 suggest that these compounds can be used as potential electrocatalytic or photocatalytic framework materials. In addition, EFISPS curves indicate that 3−5 possess the n-type semiconductor characteristic.